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TRANSCRIPT
Toralf Oheim
Jaro Stimma
Analog Chip Design
Analog Transmitter and Receiver Concepts for Wireless ChirpCommunication at 2.44GHz
10. Workshop „Analog Integrated Circuits 2008“
10.-11. March 2008 TU Berlin
Nanotron Technologies GmbH 2
Presenter
Toralf Oheim Analog/RF IC design engineer at Nanotron Technologies GmbH, Berlin
Mainly responsible for transmitter and RF oscillator design of transceiver IC‘s forwireless chirp communication at 2.44GHz
Industrial experience with design of laser driver IC‘s for fiber optic datacommunication at Infineon Technologies AG, Berlin
Study at the Technical University of Ilmenau, Theoretical Electrical Engineering, Graduation in 1993
Jaro Stimma Analog/RF IC design engineer at Nanotron Technologies GmbH, Berlin
Responsible for design of integrated analog receivers for wireless chirpcommunication at 2.44GHz
Industrial experience with design of high speed integrated analog receivers forfiber optic application at Infineon Technologies AG, Berlin
Study at Hamburg University of Applied Sciences, Graduation in 1998
Nanotron Technologies GmbH 3
Outline
1) Chirp Transmission
Chirp Transmission Technique
Transceiver IC Architecture
2) Analog Transmitter
Transmitter Architecture
Transmitter Design Concept
Transmitter Results
3) Analog Receiver
Chirp Basics
SAW Filter Characteristic
Chirp Signals in Analog RX
Nanonet TRX
(RX Heterodyne Concept)
NanoLoc TRX
(Zero IF RX Concept)
Measurement Results(Nanonet Vs. NanoLoc)
Practical Analog Design Aspects
Nanotron Technologies GmbH 4
Outline
1) Chirp Transmission
Chirp Transmission Technique
Transceiver IC Architecture
2) Analog Transmitter
Transmitter Architecture
Transmitter Design Concept
Transmitter Results
3) Analog Receiver
Chirp Basics
SAW Filter Characteristic
Chirp Signals in Analog RX
Nanonet TRX
(RX Heterodyne Concept)
NanoLoc TRX
(Zero IF RX Concept)
Measurement Results(Nanonet Vs. NanoLoc)
Practical Analog Design Aspects
Nanotron Technologies GmbH 5
Chirp Transmission Technique (1)
B
|S(f)|
f
Spectrum of the chirp pulse
Use Chirp signals for radio transmission
A chirp pulse is a frequency modulated pulse
Operation within 2.44GHz ISM band
Up-Chirp in the time domain(roll-off factor 0.25)
T
U(t)
t
The spectrum is flat
The power spectral density is very low
Optimal BT product
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Chirp Transmission Technique (2)
Upchirp = logical high
in time domain
Downchirp = logical low
in time domain
Linear frequency modulation
from fLO - B/2 to fLO + B/2
Linear frequency modulation
from fLO + B/2 to fLO - B/2
This chirp modulation technique is called:
Chirp Spread Spectrum (CSS)
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Outline
1) Chirp Transmission
Chirp Transmission Technique
Transceiver IC Architecture
2) Analog Transmitter
Transmitter Architecture
Transmitter Design Concept
Transmitter Results
3) Analog Receiver
Chirp Basics
SAW Filter Characteristic
Chirp Signals in Analog RX
Nanonet TRX
(RX Heterodyne Concept)
NanoLoc TRX
(Zero IF RX Concept)
Measurement Results(Nanonet Vs. NanoLoc)
Practical Analog Design Aspects
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Transceiver IC Architecture (nanoLOC TRX)
2.44 GHz ISM RF TRX IC
0.13Fm SiGe BiCMOS
Modulation: Chirp Spread Spectrum (CSS)
Two bandwidth modes: 80MHz/22MHz
FDMA possible (22MHz)
Several chirp durations: 0.5Fs/1Fs/2Fs/4Fs
Max. data rate: 2MBps
Low power TRX
VDD from 2.3V to 2.7V
Tamb from -40C to 85C
Package QFN 48
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Outline
1) Chirp Transmission
Chirp Transmission Technique
Transceiver IC Architecture
2) Analog Transmitter
Transmitter Architecture
Transmitter Design Concept
Transmitter Results
3) Analog Receiver
Chirp Basics
SAW Filter Characteristic
Chirp Signals in Analog RX
Nanonet TRX
(RX Heterodyne Concept)
NanoLoc TRX
(Zero IF RX Concept)
Measurement Results(Nanonet Vs. NanoLoc)
Practical Analog Design Aspects
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Transmitter Architecture
Direct conversion transmitter
Fully differential topology
6bit-DAC: fS = 244MHz
Low pass filter: Butterworth, 5th order
6
6
6
PGC
Carrier 0 and 90
6
Quadrature modulation
Power gain control circuitry
Class AB power amplifier
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Outline
1) Chirp Transmission
Chirp Transmission Technique
Transceiver IC Architecture
2) Analog Transmitter
Transmitter Architecture
Transmitter Design Concept
Transmitter Results
3) Analog Receiver
Chirp Basics
SAW Filter Characteristic
Chirp Signals in Analog RX
Nanonet TRX
(RX Heterodyne Concept)
NanoLoc TRX
(Zero IF RX Concept)
Measurement Results(Nanonet Vs. NanoLoc)
Practical Analog Design Aspects
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Low Pass Filter Design Concept (1)
Low pass filter (LPF) Butterworth 5th order:
++-
- +
+-
-
+
+-
-
+
+-
-
++-
-
RDAC
RDAC
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R RR RC1 C1 C1 C1C2 C2C2 C2 C3 C3
Conversion to active leapfrog filter structure:
Rn L2n L4n
C3nC1n C5nRn
Integration of R-DAC in first stage
R and C process deviation: calibration of C, R keeps constant
Using capacitor arrays CN with MOS switches
Calibration RC oscillator frequency
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Low Pass Filter Design Concept (2)
RDAC
OP1
C1,2
C1,1
C2,2C2,2 C3,2C1,2
OP2OP3OP4OP5
C1,1 C2,1 C3,1 C2,1
2 x 0.99mA (I and Q)CN = CN,1 + CN,2f3dB,B = 8.7MHzBB = 22MHz
2 x 1.52mA (I and Q)CN = CN,1f3dB,A = 33MHzBA = 80MHz
current consumptioncapacitor arraybandwith selectionchannel BW
Discussion: two filters or integration in one for the two channel bandwidths?
Chip area for two filter (I and Q): 0.67mm -> No
Chip area for one filter structure (I and Q): 0.45mm -> Yes
Splitting of capacitor array in two capacitor arrays: CN -> CN,1 & CN,2
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I/Q Modulation (1)
LPF_I
LPF_Q
4.88GHz
Divideby 2
0
90 RF
2.44GHz
Digital controlled oscillator
Division by 2: generation of quadrature outputs 0, 90
Gilbert cell mixers
Mixer outputs are added in current domain
DCO
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I/Q Modulation (2)
Design aspects for I/Q modulation:
Achievement of linearity in mixer
• Resistive emitter degeneration of bipolar stage at the baseband port
• IM3 <-44dBc
Preventing from I/Q phase error
• Identical layout for I and Q path
• Short interconnections betweendivider-by-2-circuit and I/Q modulator
• Post layout simulation with someiteration loops necessary
Drive LO amplitude
from LPF
IS
LO
IS
Vbias
Gilbert cell mixer
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Power Gain Control
Programmable output powerdynamic range: ≥ 33dB
6bit PGC register: 63 steps
Low power design:
Control of PA input signalamplitude in combination withcontrol of PA bias current
Gilbert cell based gain controlimplemented for amplitudecontrol
Programmable PA bias currentwith discrete current steps
VB
IS
RDAC6
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Power Amplifier Design Concept (1)
Power Amplifier (simplified): Matching and filteringcircuitry:
Balun200:50
L13.9nH
to RxN
to RxP
L25.6nH
L36.8nH
C11pF
C23.3pF
50Ω
Ant.
Vbias1
Ibias2
Ibias1
TxP
Vbias2 =1.9V
TxN
Class A Class AB
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Power Amplifier Design Concept (2)
ESD concept at PA outputs:
Two ESD diodes in seriesconnected to VDD instead of
one ESD diode as usual.
Passed ESD test conditions
Human Body Model: 2000V
Charged Device Model: 500V
Machine Model: 250V
TxP / TxN
PA
ESD
ESD
ESD
VDD
Clamp
Pad
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Outline
1) Chirp Transmission
Chirp Transmission Technique
Transceiver IC Architecture
2) Analog Transmitter
Transmitter Architecture
Transmitter Design Concept
Transmitter Results
3) Analog Receiver
Chirp Basics
SAW Filter Characteristic
Chirp Signals in Analog RX
Nanonet TRX
(RX Heterodyne Concept)
NanoLoc TRX
(Zero IF RX Concept)
Measurement Results(Nanonet Vs. NanoLoc)
Practical Analog Design Aspects
Nanotron Technologies GmbH 20
Transmitter Results (1)
TX output spectrum: TX characteristics:
TX Output Spectrum for B=80MHz / T=2µs / 500kBd
-80
-70
-60
-50
-40
-30
-20
-10
2330 2350 2370 2390 2410 2430 2450 2470 2490 2510 2530 2550
f / MHz
PS
D /
dB
m
DUT
-30dBm/100kHz
Max. Pout = +2.5dBm @50Ohm SMA
Max. PEP = +5dBm @IC output
Dynamic range = 37.5dB
-32dBr to f0 41.5MHz
2nd harmonic suppression: -56dBc
3rd harmonic suppression: -60dBc
Carrier suppression: ≤-36dBc
IDD analog = 23mA @ 80MHz
IDD TRX = 33mA @ 80MHz
IDD analog = 21.5mA @ 22MHz
IDD TRX = 29mA @ 22MHz
VDD = 2.3V … 2.7V
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Transmitter Results (2)
Measurement results of power gain control:
Typical TX Output Power at SMA Connector
-40.00
-35.00
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
5.00
0 10 20 30 40 50 60
PGC Register Value /dec
Po
ut
/dB
m
Typical Current Consumption
15.00
17.00
19.00
21.00
23.00
25.00
27.00
29.00
31.00
33.00
35.00
0 10 20 30 40 50 60
PGC Register Value /dec
IDD
/m
A
IDD total
IDD analog
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Outline
1) Chirp Transmission
Chirp Transmission Technique
Transceiver IC Architecture
2) Analog Transmitter
Transmitter Architecture
Transmitter Design Concept
Transmitter Results
3) Analog Receiver
Chirp Basics
SAW Filter Characteristic
Chirp Signals in Analog RX
Nanonet TRX
(RX Heterodyne Concept)
NanoLoc TRX
(Zero IF RX Concept)
Measurement Results(Nanonet Vs. NanoLoc)
Practical Analog Design Aspects
Nanotron Technologies GmbH 23
A chirp pulse is a frequency modulated pulse
Up-Chirp in the time domain(roll-off factor 0.25)
Spectrum of the chirp pulse withbandwidth B and a roll-off factor of 0.25
BW
S(f)
f
Chirp Basics 1
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A Simple procedure transforms the Chirp into a (Sinc-)Pulse
t
Chirp
t
U(t)
Sinc-PulseDispersive Delay Line
Chirp Basics 2
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Outline
1) Chirp Transmission
Chirp Transmission Technique
Transceiver IC Architecture
2) Analog Transmitter
Transmitter Architecture
Transmitter Design Concept
Transmitter Results
3) Analog Receiver
Chirp Basics
SAW Filter Characteristic
Chirp Signals in Analog RX
Nanonet TRX
(RX Heterodyne Concept)
NanoLoc TRX
(Zero IF RX Concept)
Measurement Results(Nanonet Vs. NanoLoc)
Practical Analog Design Aspects
Nanotron Technologies GmbH 26
SAW Filter for T=1us and BW=80MHz
Frequency ResponseGroup Delay Characteristic
Impact of the Test Environment
UP – ChannelDOWN - Channel
UP – ChannelDOWN - Channel
Statistical Data of 20 Components
80MHz
190 250 310 f [MHz]220 250 280 f [MHz]
1us
80MHz
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Outline
1) Chirp Transmission
Chirp Transmission Technique
Transceiver IC Architecture
2) Analog Transmitter
Transmitter Architecture
Transmitter Design Concepts
Transmitter Results
3) Analog Receiver
Chirp Basics
SAW Filter Characteristic
Chirp Signals in Analog RX
Nanonet TRX
(RX Heterodyne Concept)
NanoLoc TRX
(Zero IF RX Concept)
Measurement Results(Nanonet Vs. NanoLoc)
Practical Analog Design Aspects
Nanotron Technologies GmbH 28
Chirp Signals in Analog RX 1
Up DownUp UpUp
Down
SAW FILTER
IF AM Signal
fIF=250MHz; BWMAX=80MHz
IF FM SignalfIF=250MHz;BWMAX=80MHz
O11 O 1
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Chirp Signals in Analog RX 2
Zero IF Quadratur Downconversion
Up UpDown Down Up
101 1 0
I
Q
RF FM Signal(fRF=2,442GHz;BWMAX=80MHz)
Baseband “FM – Signal”
(BWMAX=40MHz)
900fLO=fRF=2,442GHz
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Outline
1) Chirp Transmission
Chirp Transmission Technique
Transceiver IC Architecture
2) Analog Transmitter
Transmitter Architecture
Transmitter Design Concepts
Transmitter Results
3) Analog Receiver
Chirp Basics
SAW Filter Characteristic
Chirp Signals in Analog RX
Nanonet TRX
(RX Heterodyne Concept)
NanoLoc TRX
(Zero IF RX Concept)
Measurement Results(Nanonet Vs. NanoLoc)
Practical Analog Design Aspects
Nanonet RX (Heterodyne Concept)
RX RF
RX ANALOG BASEBAND
RX IF
fLO=fRF+fIF=2.692GHz
fRF = 2.442GHz
fIF = 250MHz
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Advantages of Heterodyne Nanonet RX
Current Consumption of Chirp Correlator (SAW Filter) 0mA
Very Good IF BP Characteristic due to SAW Filter
AC coupling in the IF circuitry possible (small C values)
Low Flicker Noise due to IF
Short RXON Settling time
Relative Simple Analog AM-Chirp Detector
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Disadvantages of Heterodyne Nanonet RX
Constant Chirp BW and Chirp Duration because of SAW
SAW Filter = External Component
SAW – Driver required
Image Rejection Aspect ISM BPF
Higher Current Consumption of IF Amplifiers
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Heterodyne RX Design in 0,35um SiGe BiCMOS
Full Differential Variable Gain LNA with LC Load
I=4,5mA;NF=1,8dB@150;fo=2,44GHz;BW=320MHz;Gain=12…26dB;
Full Balanced Gilbert Cell Mixer
I=1,2mA; NF=5dB; Conversion Gain=15dB;
Full Differential AC Coupled Variable Gain Amplifiers
I=1,6mA@BW=450MHz; fo=250MHz; Gain=1…15dB;
AM – Chirp Detector with programmable detection threshold I=0,75mA
High Speed CMOS Comparator
I=0,45mA
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Outline
1) Chirp Transmission
Chirp Transmission Technique
Transceiver IC Architecture
2) Analog Transmitter
Transmitter Architecture
Transmitter Design Concept
Transmitter Results
3) Analog Receiver
Chirp Basics
SAW Filter Characteristic
Chirp Signals in Analog RX
Nanonet TRX
(RX Heterodyne Concept)
NanoLoc TRX
(Zero IF RX Concept)
Measurement Results(Nanonet Vs. NanoLoc)
Practical Analog Design Aspects
NanoLoc Receiver (Zero IF RX Concept)
RX RF (BWMAX=80MHz)
RX ANALOG BASEBAND (BWMAX=40MHz)0 90
fLO=fRF=2.442GHz
fRF=2.442GHz
DIGITALCHIRPCORRELATOR
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Advantages of Zero IF RX
Variable Chirp Bandwidth and Chirp Duration because of programmable Digital Correlator
No Image Rejection Filter
No External Components (SAW) for RX necessary
No Output Drivers
Relatively Low BW of Baseband Amplifiers
Digital AGC (because of ADC)
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Disadvantages of Zero IF RX
DC Offset Cancellation and RX Settling Time Aspect
Flicker Noise
Programmable Anti - Aliasing Filter required
Higher Power Consumption of the Digital Chirp Correlator
ADC Crosstalk Aspect Power Supply Isolation
High Layout Effort for Optimal Matching within the Circuitry
Power Consumption and High Speed Vs. Large L – Values of CMOS Transistors in the Baseband Circuitry
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Zero IF RX Design in 0,13um SiGe BiCMOS
Full Differential Variable Gain LNA with LC Load
I=4,5mA; NF=1,9dB@200; fo=2.44GHz; BW=225MHz; Gain=14..28dB;
Resolution=2dB;
Full Balanced Gilbert Cell Mixers
I=1,1mA; NF=4,8dB@10MHz; Conversion Gain=13dB;
Programmable Differential Leap Frog Low Pass Filter (Butterworth 5th Order)
see TX slides
Full Differential Variable Gain Amplifiers
I=0,2mA@BW=190MHz; Gain=1..15dB; Resolution=2dB;
Full Differential Active High Pass Filters for DC Cancellation
I=500nA@f-3dB=25kHz;
Full Differential 5Bit Flash ADC
ITOTAL=4,2mA@0,28um CMOS; Sampling Frequency=122MHz; DR=30dB;
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Outline
1) Chirp Transmission
Chirp Transmission Technique
Transceiver IC Architecture
2) Analog Transmitter
Transmitter Architecture
Transmitter Design Concept
Transmitter Results
3) Analog Receiver
Chirp Basics
SAW Filter Characteristic
Chirp Signals in Analog RX
Nanonet TRX
(RX Heterodyne Concept)
NanoLoc TRX
(Zero IF RX Concept)
Measurement Results(Nanonet Vs. NanoLoc)
Practical Analog Design Aspects
Measurement Results @ Nominal Conditions
*) ADC Design in 0,28um CMOS instead of 0,13um **) Simulation Results
-40C … +85C-40C … +85CAmbient Temperature Range
2.3V … 2.7V2.4V … 3.6VVoltage Supply Range
-9dBm-17dBmIIP3 of analog RX **)
2,3dB @ 200ohms2,4dB @ 150ohmsNF of RX @ w/o. TX Load **)
2,9dB @ 200ohms3,0dB @ 150ohmsNF of RX @ incl. TX Load
45mA35mACurrent Consumption of Complete RX
28mA *)27mACurrent Consumption of Analogue RX incl. Freq.Synthesizer
22mA *)21mACurrent consumption of Analog RX (Signal Path)
NanoLoc (Zero IF RX)@ 0,13um SiGe BiCMOSft,BIP=45GHz
Nanonet (Heterodyne RX)@ 0,35um SiGe BiCMOSft,BIP=45GHz
Electrical
Parameters
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Outline
1) Chirp Transmission
Chirp Transmission Technique
Transceiver IC Architecture
2) Analog Transmitter
Transmitter Architecture
Transmitter Design Concept
Transmitter Results
3) Analog Receiver
Chirp Basics
SAW Filter Characteristic
Chirp Signals in Analog RX
Nanonet TRX
(RX Heterodyne Concept)
NanoLoc TRX
(Zero IF RX Concept)
Measurement Results(Nanonet Vs. NanoLoc)
Practical Analog Design Aspects
Nanotron Technologies GmbH 43
Practical Analog Design Aspects
Concept of the LNA Input RX/TX Switch
Requirements :
- Ron< 6- Good ESD Protection
- Low Parasitic Capacitance
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(IO NMOS = NMOS
with unsalicided
drain and source
area for good ESD
protection)
Drawback:
- Insufficient HF Model for IO NMOS
- High Parasitic Capacitance
Benefits :
- High ESD Protection
- Low Ron (Large W/L)
Practical Analog Design Aspects
Realisation of the LNA input switch using an IO NMOS
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(RF NMOS = NMOS
with well RF model
and bad ESD
protection)
Drawback :
- Additional High Ohmic Resistors
for Drain- and Source – ESD
protection required
- High Ron
- High Parasitic Capacitance
Benefits :
- High ESD Protection
- Well HF Model of the Switch
Circuitry
Practical Analog Design Aspects
Realisation of the LNA input switch using a RF NMOS
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Drawback :
- Large and Tricky Layout
Benefits :
- Low Ron
- High ESD Protection
- Sufficient HF Model of the
Switch Circuitry
Practical Analog Design Aspects
Switches in Parallel for Low Ron Resistance Value
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Peak Over Mean - Chirp Detection (UP- or DOWN- Channel)
0
1
IF AM Signal
fIF=250MHz;
BWMAX=80MHz
IF PeakDetector
MeanDetector
R
SIGNAL
Comparator
THRESHOLD
RDAC
Practical Analog Design Aspects
Digital
BasebandSignal
TO DIGITAL
1
1
Rectifier
1 0
0 0
Good Experiences with Emitter Degeneration - Controlled Gain:• Simple Programmable Emitter Degeneration• Output DC Voltage independant of Gain• Gain dependence on process variation very low• Higher Linearity at Higher Input Level• Simple Topology
Variable Gain Amplifier for Baseband Application
VS
Practical Analog Design Aspects
Thank You !